The golden goblet Why the wounds on Ranofer's back embarrass him?

The wounds on Ranofer's back embarrass him because they are a physical representation of his abusive treatment by Gebu, his half-brother and guardian. Ranofer feels ashamed of his bruises and scars because they remind him of his vulnerability and powerlessness in his situation. Additionally, Ranofer doesn't want others to see his injuries as it may lead to questions about his home life and reveal the truth about his mistreatment.